Fluid pump with fluid returned pistons



Jam. 28, 1958 H. M. PURCELL. 2,821944 FLUID PUMP WITH FLUID RETURNED 4PIS'IOS Filed Nov. 1e, 1955 INI/Emma.` lHOWARD M. PURCELL WNW-M LM ams. l

raum PUMP wirn trium nnrunsso risronts Howard M. Purcell, Mount Gilead, hio, assigner, by mesue assignments, to Koehring Company, Pvililwaunee, Wis., a corporation of 'Wisconsin Application November lo, i955, Serial No. 547,195

S Claims. (Cl. 10S- 162) The invention relates in general to iiuid pumps and more particularly to fluid pumps having pump pistons which are actuated on an intake stroke by fluid means responsive to the fluid pressure in the discharge passage- Way of the pump and iirst valve means for maintaining a predetermined positive pressure in` discharge end of the pump and second valve means for insuring that only a predetermined pressure is communicated from the dis- Charge passageway to the uid means for returning the pump pistons.

An obiect of the invention is tovprovide a fluid pump with valve means whereby a predetermined pressure will be present in the discharge passageway of the pump regardlessof whether the pump is running or stopped.

Another object of the invention is to provide a iiuid pump having fluid entendible means actuated by tluid pressure from the discharge passageway of the pump with aivalve member for regulating the rluid pressure fromV the discharge passageway to the lluid entendible means.

Another object of the invention is to provide a iluid pump, wherein pump pistons are actuated on a high pres sure discharge stroke in one direction by cam means and actuated on an intake stroke by lluid entendible means which uidy extendible means are in fluid communication with the high pressure discharge passageway and are actuated thereby, with valve meansY tot maintaining a positive pressure in the. discharge passageway whereby the :duid extendible means are actuated whether the pump is. running or stopped and also to provide a valve member which is responsive to the fluid pressure n the discharge passageway and which will close oi the communication between the discharge passageway and the fluid extendible means upon the building up of a predeterminedpressure in the discharge. passageway and thus prevent damage to the duid extendible means or undue resistance to the movement of the pump pistons on their discharge stroke.

Figure l is a side elevation view in section of a fluid pump incorporatingtheprinciples of the invention;

Figure 2 is a View taken. along the line 2-2ot` Figure l;

Figure 3 is a fragmentary View in section takenv generally along the line 3-3 of Figure 2.

The fluid piunp of this invention is indicated generally by the reference numeral. lll and includes a housing il and an insert member l2 located within the housing. A rotor l5 which has a plurality of pump cylinders le is mounted about and surrounds the insert members l2. The pump cylinders inthe accompanying drawings have all been identified with the reference numeral Th pump cylinders lo are located about the periphery of the rotor l5 and extend generally axially within the rotor. A rst and a second pump piston 2i? and 2i respectively are mounted within each or" the pump cylinders le. Cam means 23 which include cam members 2d and 25 are mounted on the'nner walls of the housing li'. The cam means 23 are engageable with the iirst and second pump pistons Ztl and. 2l respectively whichk are locatedl ldid atented Jan. 28, 1958 in each of the pump cylinders 16 and as the rotor rotates about the insert member l2 the cam means move the first and second pump pistons toward each other on a discharge stroke. An intake passageway 3u and rst and second discharge passageways 3l and 32 respectively are located within the insert member 12. Port means 33 extend from the pump cylinders i6 for providing alternate communication of the pump cylinders 16 with the intake and discharge passageway. The rst and second discharge passageways 3l and 32 respectively extend from the Central portion of the insert member 12 as separate passageways and are joined together at an end portion of the insert member and flow from the discharge side of the pump in a single passageway 3f.

Fluidmeans or fluid extendible means indicated generally by the reference numeral 37 are provided for returning the pump pistons 20 and Zi on an intake stroke so that these pump pistons will. be maintained in engagement with the cam means 23. The fluid entendible means 37 includes a fluid chamber 38 within the first pump piston 29 in each of the pump cylinders lo and a piston rod 36 in each of the pump cylinders le. The piston red 39 in eachr of the pump cylinders 16 has a iirst and a second end portion lil and il respectively. The piston rods 39k extend axially within each of the pump cylinders i6 with the first end portion lli slidably communicating with the tluid chamber 38 through an opening l2 within an end portion. of the first pump piston Ztl. rlh-e second end portion 4l is engageable with or may be xediy attached to the second pump piston 2l. Conduit means indicated generallyv by the reference numeral 457 connect the discharge passageway 3l and frespectively and the fluid chambers 38 which are located in each of the rst pump pistons 2li together and as a result will provide the fluid chambers 33 with lluid pressure from these discharge passageways. This fluid pressure within the fluid chamber in the rst pump pistons acts upon an end face e3 of the piston rod 39 and upon an end wall 4d of the duid chamber 33 which is located opposite of the face 43 of the piston-rod 3 for maintaining the first and second pump pistons in each pumpL cylinder in engagement with the rst and second cam members 2d and 2S respectively. IThe conduit means i7 includes a conduit 4S which extends from the discharge passageway through the insert member l2 and into an annular space i9 within the rotor member l5. rhe annular space 49 is in turn connected tothe lluid chamber 3S in each of the rst pump pistons 2in by means of passageways 5l?, A drive shaft 54E extends through the housing il and is mounted upon suitable bearings $5 and 55 for rotation thereon. This river shaft may be driven from any suitable power source. The drive shaft i5 is connected to the rotor l5 for rotating the rotor about the insert member l2 by means of a connection member :57.

It will be noted that when there is iluid pressure at the.

discharge end of the pump that there will also be uid pressure communicated to the fluid chambers 3S by way of the conduit means 47. however the pressure in the discharge end of the pump would normally drop down to atmospheric pressure which would result in the same pressure in the iluid chambers 3S. As a result the first and second pump pistons 23 and il in each of 'the pump cylinders lo would tend to collapse or stay in the position in which they will be located at the end of the discharge stroke. This position is best illustrated in Figure l. Figure 3 shows the rotor l5' rotated 9G degrees with respect to the position shown in Figure l. 6l) has been provided to cooperate with the discharge end of the pump and includes a check valve 51 which is urged toward a closed position by a spring 52, This spring 62 When the pump is stopped.

To obviate this possibility a rst valve meansv may be of any predetermined value and provides that a certain iiuid pressure will be maintained at the discharge end of the pump at all times and hence will maintain fluid pressure in the iiuid chamber 38 at all times and as a result the first and second pump pistons will be maintained in engagement with the cam means 23 for all operating conditions of the pump. For example, if the pump was normally to operate to deliver duid at 2,009 pounds per square inch pressure the spring 62 could be set as to always maintain a fluid pressure in the discharge end of the pump of 100 pounds per square inch. This means that there would be 1GO pounds per square inch pressure in the iuid chambers 38 at all times insuring that the pump pistons will always be positively maintained against the cam means 23.

Another` problem which must be guarded against is that of undue uid pressure from the discharge end of the pump entering the fluid chambers 38 by way of the conduit means 47. If too much pressure is communicated to the iluid chambers 38 the iiuid extendible means could be severely damaged. In addition to that, if a large amount of pressure is communicated to these chambers a great amount of opposition will be encountered by the cam means 23 trying to move the pump pistons on the discharge stroke. As a result of these problems second valve means 66 have been provided for cooperating with the conduit means 47 for opening and closing the conduit means. The second valve means 66 includes a bore 67 and a valve member 68 located therein. The valve member 68 has a first and a second face 69 and 70 respectively. The valve member 68 also has an opening 71 which extends from the iirst face 69 and communicates with an annular slot 72 about the outer periphery of the valve member 68. This annular slot 72 in turn communicates with the conduit means 47 which leads on through to the uid chambers 38. A spring 73 as best shown in Figure l normally biases the valve member 68 to the left in an open or rst position whereby the uid pressure from the discharge passageway is communicated through to the uid chambers 38. The first face 69 of the valve member 68 communicates with the fluid pressure in the discharge passageway and is responsive thereto. In other words when a suicient predetermined uid pressure has been built up in the discharge passageway this uid pressure acting on the rst face 69 overcomes the force of the spring 73 and subsequently moves the valve member to the right from the position which it is in as seen in Figure l. As the valve member 68 moves to the right the annular slot 72 moves to a second position which is out of communication with the conduit means 47 which leads from lthe valve member to the fiuid chamber 38. As a result of this movement to the second or closed position by the valve member 68 further iiuid pressure is prevented from passing from the discharge passageway to the fluid chambers 38 and as a result none of the herein above mentioned diculties will be encountered. The spring loaded Valve 74 provides communication between the passageways 50 and the interior of the pump housing 11. This spring loaded valve member 74 insures that upon a predetermined pressure build up it will open and vent the pressure to the housing 11. This insures that excessive pressure build up will not be allowed in either of the chambers 38 or the passageways 50.

It will therefore be readily apparent that a unique and novel means has been provided for positively maintaining iuid pressure in the discharge passageway of the pump, therefore always maintaining the pump pistons in engagement with the cam means. The pump pistons will therefore always be in a position to pump fluid upon rotation of the rotor by means ofthe driver shaft 54. The additional provision of the second valve means within this type ol pump always provides that undue pressure from the discharge passageways will not be communicated to the fluid extendible means which assist in maintaining the pump pistons positively against the cam means.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

vWhat is claimed iS:

l. In a uid pump including a housing, an insert member within said housing, a rotor having a plurality of pump cylinders and surrounding said insert member, a rst and a second pump piston mounted within each said pump cylinder, cam means engageable with said first and second pump pistons for moving said iirst and second pump pistons toward each other on a discharge stroke, an intake and a discharge passageway located within said insert member, port means extending from each Said pump cylinder for alternate communication with said intake and discharge passageways, said rst pump piston in each said pump cylinders having a fluid chamber therein, a piston rod in each said pump cylinder and having a rst and a second end portion, each said piston rod extending axially within each said cylinder with said first end portion communicating with said fluid chamber in telescoping relationship thereto and said second end portion engaging said second pump piston, conduit means connecting said discharge passageway and each saidV iuid chamber together thereby providing said fluid chambers with fluid pressure from said discharge passageway wherby said first and second pump pistons in each said pump cylinder are maintained in engagement with said cam means on an intake stroke, a spring loaded check valve cooperating with said discharge passageway for maintaining a predetermined uid pressure in said discharge passageway at all times and hence maintaining uid pressure in said uid chambers whereby said first and second pump pistons in each said pump cylinder are maintained in engagement with said cam means at all times, a valve member cooperating with said conduit means and movable between a rst and a second position for opening and closing said conduit means, spring means normally maintaining said Valve member in said iirst position thereby providing uid communication between said discharge passageway and said uid chambers, said valve member responsive to uid pressure within said discharge passageway whereby upon sucient pressure build up within said discharge passageway said spring means is overcome and said valve member moves to said second position shutting oh fluid communication between said discharge passageway and said fluid chambers.

2. In a fluid pump including a housing, an insert member within said housing, a rotor having a pump cylinder and surrounding said insert member, a first and a second pump piston mounted within said pump cylinder, cam means engageable with said rst and second pump pistons for moving said rst and second pump pistons on a discharge stroke, an intake and a discharge passageway in the housing, port means in said rotor extending 'om said pump cylinder for alternate communication With said intake and discharge passageways incident to the rotation of the rotor, said first pump piston having a fluid chamber therein, a piston rod having a first and a second portion, said first end portion of said piston rod communicating with said uid chamber in telescoping relationship thereto and said second end portion of said piston rod engageable with said second pump piston, conduit means connecting said discharge passageway and said iiuid chamber together thereby providing said uid chamber with fluid pressure from said discharge passageway whereby said rst and second pump pistons in each said pump cylinder are maintained in engagement with said cam means, discharge passageway valve means cooperating with said discharge passageway for maintaining uid pressure in said discharge passageway and hence maintaining fluid prersure in said uid chambers whereby said first and second pump pistons in each said pump cylinder are maintained in engagement with said cam means, conduit valve means cooperating with said conduit means and movable between a first and a second position for opening and closing said conduit means, means normally maintaining said conduit valve means in. said first position thereby providing uid communication between said discharge passageway and said fluid chamber, said conduit valve means responsive to fluid pressure within said discharge passageway whereby upon sufficient pressure build up within said discharge passageway said means which normally maintain said conduit valve means in saidrst position is overcome and said conduit valve means moves to said second position shutting ofi fluid communication between said discharge passageway and said iiuid chamber.

3. In a iiuid pump including a housing, an insert member within said housing, a rotor having a plurality of pump cylinders, a first and a second pump piston mounted within each said pump cylinder, cam means engageable with said irst and second pump pistons for moving said first and second pump pistons toward each other on a discharge stroke, an intake and a discharge passageway in the housing, port means in said rotor extending from each said pump cylinder for alternate communication with said intake and discharge passageways in the rotation of said rotor, said rst pump piston in each said pump cylinders having a iiuid chamber therein, a piston rod in each said pump cylinder and having a first and a second end portion, each said piston rod extending axially within each said cylinder with said first end portion communicating with said fiuid chamber in telescoping relationship thereto and said second end portion engageable with said second pump piston, conduit means connecting said discharge passageway and each said fluid chamber together thereby providing said iluid chambers with fluid pressure from said discharge passageway whereby said first and second pump pistons in each said pump cylinder are maintained in engagement with said cam means, discharge passageway valve means cooperating with said discharge passageway for maintaining fiuid pressure in said discharge passageway and hence maintaining uid pressure in said fluid chambers whereby said first and second pump pistons in each said pump cylinder are maintained in engagement with said cam means.

4. In a fluid pump including a housing, an insert member within said housing, a rotor having a plurality of pump cylinders and surrounding said insert member, a first and a second pump piston mounted within each said pump cylinder, cam means engageable with said first and second pump pistons for moving said iirst and second pump pistons toward each other on a discharge stroke, an intake and a discharge passageway located within said insert member, port means extending from each said pump cylinder for alternate communication with said intake and discharge passageways, said first pump piston in each said pump cylinders having a fluid chamber therein, a piston rod in each said pump cylinder and having a first and a second end portion, each said piston rod extending axially within each said cylinder with said rst end portion communicating with said fluid chamber in telescoping relationship thereto and said second end portion engaging said second pump piston, conduit means connecting said discharge passageway and each said iiuid chamber together thereby providing said duid chambers with fluid pressure from said discharge passageway whereby said iirst and second pump pistons in each said pump cylinder are maintained in engagement with said cam means, conduit valve means cooperating with said conduit means and movable between a first and a second position for opening and closing t@ said conduit means, urging means normally maintaining said conduit valve means in said first position thereby providing fiuid communication between said discharge passageway and said fluid chambers, saidl conduit valve means responsive to fluid pressure within said discharge passageway whereby upon sufficient pressure build up within said discharge passageway said urging means is overcome and said conduit valve means moves to said second position shutting od iiuid communication between said discharge passageway and said fluid chambers.

5. In a iiuid pump having first and second pump pistons movable axially within a pump cylinder on a discharge stroke by cam means to discharge fluid to a discharge passageway at a higher pressure than which it is received within the pump cylinder; means for maintaining said first and second pump pistons in` engagement with said cam means at all times operatively interposed between said first and second pump pistons in said cylinder and comprising a fluid chamber within said first pump piston, a piston rod at one end thereof communicating with said chamber in telescoping relationship thereto, said piston rod being abuttable with said second pump piston at the other yend thereof, conduit means connecting said iiuid chamber and said discharge passageway together whereby fluid pressure from said discharge passageway is communicated to said iiuid chamber, and discharge passageway valve means in said discharge passageway to provide a predetermined uid pressure at all times in said discharge passageway and hence a fluid pressure in said fluid chamber at all times.

6. In a fluid pump having first and second pump pistons movable axially within a pump cylinder on a discharge stroke by cam means to discharge iiuid to a discharge passageway at a higher pressure than which it is received within the pump cylinder; means for maintaining said first and second pump pistons in engagement with said cam means at all times operatively interposed between said first and second pump pistons in said cylinder and comprising a fluid chamber within said first pump piston, a piston rod at one end thereof communicating with said chamber in telescoping relationship thereto, said piston rod being abuttable with said second pump piston at the other end thereof, conduit means connecting said fluid chamber and said discharge passageway together whereby fluid pressure from said discharge passageway is communicated to said uid chamber, and conduit valve means in said conduit means and movable vbetween a first and a second position for alternatively permitting and prohibiting fluid communication between said discharge passageway and said iiuid chamber.

7. In a iiuid pump having first and second pump pistons movable within a pump cylinder on a discharge stroke by cam means to discharge fluid to a discharge passageway at a higher pressure than which is received within the pump cylinder; means for maintaining said first and second pump pistons in engagement with said cam means operatively interposed between said first and second pump pistons in said pump cylinder and comprising a iiuid chamber within said first pump piston, a piston rod at one end portion thereof communicating with said fluid chamber in telescoping relationship thereto, said piston rod being abuttable with said second pump piston at the other end portion thereof, conduit means connecting said iiuid chamber and said discharge passageway together whereby fluid pressure from said discharge passageway is communicated to said iiuid chamber, discharge passageway valve means cooperating with said discharge passageway to provide a predetermined fluid pressure in said discharge passageway and hence a iiuid pressure in said tiuid chamber, and conduit valve means cooperating with said conduit means to alternatively permit and prohibit fluid communication between said discharge passageway and said fiuid chamber.

8. In a fluid pump having pump piston means movable Within a pump cylinder on a discharge stroke by cam means to discharge uid to a discharge passageway at a higher pressure than which it is received within the pump cylinder; means for maintaining said pump piston means in engagement with said cam means at all times operatively disposed adjacent said piston means in said pump cylinder and comprising fluid extendible means including a uid chamber formed in said pump piston means, a piston rod having one end disposed in telescoping relationship within said chamber and adapted to be pro jected endwise therefrom relative to the piston upon introduction of pressure uid into said chamber, discharge passageway together whereby uid pressure from said discharge passageway is communicated to said uid chamber, and discharge passageway valve means in said discharge passageway to provide a predetermined tluid pressure in said discharge. passageway and hence a fluid pressure in said uid chamber at all times.

. References Cited in the le of this patent UNITED STATES PATENTS 1,297,700 i Larsson Mar. 18,1919 1,362,040 Pratt Dec. 14, 1920 2,129,886 Syrovy Sept. 13, 1938 2,155,455 Thoma Apr. 25, 1939 2,284,111 Vickers May 26, 1942 2,439,668 Mercer Apr. 13, 1948 2,459,786 Beaman et al. Jan. 25, 1949 2,577,242 Grad Dec. 4, 1951 FOREIGN PATENTS 707,462 Germany `Tune 23, 1941 U. s. nEnBTnENT 0F coMMEBcE =M TEJT OFFICE CERTIFIQLTB 0F coRREc'rIoN Patentino. 2,821,144 f j January 28, 195s Ibwed M., Purcell i It i'e hereby certified dat Arror appears in the printed specification of the above numbered patent raql'irng correction and that the said Letters vPatent should read as corrected HBlOW.

Column 3, line 9, after "S" insert so column 4, line 66, before "portion", first occurremey insert m end signed and Sealed this letfdey of April 1958.

(SEAL) Attest:

KRLH. AXLINE ROBERT C. WATSON Attestng Officer Conmissioner of Patents 

